This invention relates in general to beds and in particular, to beds of the type that articulate to change the orientation of the sleep surface. Most particularly, the invention relates to the kinematic motion of articulated beds.
Articulated beds are well known. A conventional articulated bed includes a sleep surface supported by a main frame. The main frame is supported by a pair of opposing legs. A typical sleep surface includes a head section, a foot section, and a knee section between the head and foot sections. The head and knee sections are pivotally supported by a main frame so that they may be raised and lowered relative to the main frame. The foot section is pivotally connected to the knee section so that it moves in response to movement of the knee section. In addition to the sleep surface being movable, the legs of the bed are movable. Movement of the legs changes the orientation of the main frame by raising, lowering, or tilting the main frame.
The physical structure of the articulated bed limits its ability to achieve desired minimum and maximum elevations. For example, forces acting upon the legs are greatest when the bed first begins to rise from its lowest position. These forces resist movement of the legs if the angular disposition of the legs is too great. As the legs come closer to being horizontal when the bed is in its lowered position, a greater amount of force is required to start the legs in motion to raise the bed. The force can become so great that an affordable mechanical means for displacing the legs could be ineffective.
What is needed is a low-cost structure for an articulated bed that minimizes the amount of force required to raise the bed from its lowered position.
The present invention is directed towards a low-cost structure for an articulated bed which minimizes the elevation of the bed when in a lowered position and maximizes the elevation of the bed when in a raised position while minimizing the amount in which the bed creeps and further while maximizing leverage and minimizing force required to raise the bed from its lowered position. The articulated bed comprises a main frame supported by a leg tube. An upper portion of the leg tube is longitudinally and pivotally displaceable relative to the main frame at an upper movable pivot point. A lower portion of a stabilizer is connected to a lower intermediate portion of the leg tube at a lower orbital pivot point. An upper portion of the stabilizer is pivotally connected relative to the main frame at an upper fixed pivot point. A wheel is pivotally attached to a lower portion of the leg tube at a pivot axis. The upper movable pivot point, the lower orbital pivot point, and the pivot axis do not coalign and the distance between the upper fixed pivot point and the upper movable pivot point are maximized when the main frame is in a raised position.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.